Elachista is a genus of gelechioid moths described by Georg Friedrich Treitschke in 1833. It is the type genus of the grass-miner moth family (Elachistidae). This family is sometimes (in particular in older sources) circumscribed very loosely, including for example the Agonoxenidae and Ethmiidae which seem to be quite distinct among the Gelechioidea, as well as other lineages which are widely held to be closer to Oecophora than to Elachista and are thus placed in the concealer moth family Oecophoridae here. These grass-miners are very small moths with the "feathery" hindwings characteristic of their family. They are essentially found worldwide, except in very cold places and on some oceanic islands; as usual for Gelechioidea, they are most common in the Palearctic however. They usually have at least one, sometimes as many as three light bands running from leading to trailing edge of their forewing uppersides. Some species, however, have upper forewings that are mostly white. Selected species Not all species of this large genus have been discovered yet, let alone validly described and named. Several small genera, e.g. Biselachista and Cosmiotes, are here included in Elachista as junior synonyms (see below). They seem to be at least as closely related to E. bifasciella (the type species of the present genus) than other species commonly placed here, if not actually closer. In addition, Elachista contains several cryptic species complexes – such as the one around E. dispunctella and E. triseriatella – whose systematics and taxonomy are still not fully resolved. A number of Elachista species have been assigned to one of several groups, which may or may not be monophyletic, and whose names in the literature do not consistently follow the usual taxonomic practice (i.e. using as namesake the group-member which was described first). Some of these groups are placed in either of the two large subgenera Elachista (Aphelosetia) and Elachista (Elachista). Other proposed subgenera – the small Elachista (Dibrachia) and Elachista (Hemiprosopa) – are here included in the species of unclear relationships; like some small species-groups, they stand a chance of rendering the two larger subgenera paraphyletic if accepted as distinct, but seem too unlike them to warrant placement in either. Subgenus Elachista (Aphelosetia)argentella group (sometimes in bedellella group) Elachista acenteta Elachista achrantella Elachista adempta Elachista adianta Elachista anagna Elachista aphyodes Elachista apina Elachista arena Elachista argentella (type of Aphelosetia) Elachista argillacea Elachista aspila Elachista aurocristata Elachista conidia Elachista coniophora